Move spell checker in core/editing/ related files into core/editing/spellcheck/

Source/core/core.gypi

Index: Source/core/core.gypi
diff --git a/Source/core/core.gypi b/Source/core/core.gypi
index 0d511143b831cc94106d28ac174d18699f85d9f8..d0c56c968994ffc5e3e2bdb3c3798f888f6c4d0e 100644
--- a/Source/core/core.gypi
+++ b/Source/core/core.gypi
@@ -1381,10 +1381,6 @@
             'editing/SimplifyMarkupCommand.cpp',
             'editing/SmartReplaceCF.cpp',
             'editing/SmartReplaceICU.cpp',
-            'editing/SpellCheckRequester.cpp',
-            'editing/SpellCheckRequester.h',
-            'editing/SpellChecker.cpp',
-            'editing/SpellChecker.h',
             'editing/SplitElementCommand.cpp',
             'editing/SplitElementCommand.h',
             'editing/SplitTextNodeCommand.cpp',
@@ -1397,8 +1393,6 @@
             'editing/StyledMarkupSerializer.h',
             'editing/SurroundingText.cpp',
             'editing/SurroundingText.h',
-            'editing/TextCheckingHelper.cpp',
-            'editing/TextCheckingHelper.h',
             'editing/TextInsertionBaseCommand.cpp',
             'editing/TextInsertionBaseCommand.h',
             'editing/TextOffset.cpp',
@@ -1414,6 +1408,12 @@
             'editing/VisibleUnits.cpp',
             'editing/WrapContentsInDummySpanCommand.cpp',
             'editing/WrapContentsInDummySpanCommand.h',
+            'editing/spellcheck/SpellCheckRequester.cpp',
+            'editing/spellcheck/SpellCheckRequester.h',
+            'editing/spellcheck/SpellChecker.cpp',
+            'editing/spellcheck/SpellChecker.h',
+            'editing/spellcheck/TextCheckingHelper.cpp',
+            'editing/spellcheck/TextCheckingHelper.h',
             'fetch/AccessControlStatus.h',
             'fetch/CSSStyleSheetResource.cpp',
             'fetch/CSSStyleSheetResource.h',